Re: [patch 12/15] LTTng instrumentation - hugetlb (update)

From: Mathieu Desnoyers
Date: Fri Jul 11 2008 - 10:30:30 EST

Instrumentation of hugetlb activity (alloc/free/reserve/grab/release).

Those tracepoints are used by LTTng.

About the performance impact of tracepoints (which is comparable to markers),
even without immediate values optimizations, tests done by Hideo Aoki on ia64
show no regression. His test case was using hackbench on a kernel where
scheduler instrumentation (about 5 events in code scheduler code) was added.
See the "Tracepoints" patch header for performance result detail.

Changelog :
- instrument page grab, buddy allocator alloc, page release.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
CC: William Lee Irwin III <wli@xxxxxxxxxxxxxx>
CC: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
CC: 'Peter Zijlstra' <peterz@xxxxxxxxxxxxx>
CC: "Frank Ch. Eigler" <fche@xxxxxxxxxx>
CC: 'Ingo Molnar' <mingo@xxxxxxx>
CC: 'Hideo AOKI' <haoki@xxxxxxxxxx>
CC: Takashi Nishiie <t-nishiie@xxxxxxxxxxxxxxxxxx>
CC: 'Steven Rostedt' <rostedt@xxxxxxxxxxx>
CC: Eduard - Gabriel Munteanu <eduard.munteanu@xxxxxxxxxxx>
---
mm/hugetlb-trace.h | 28 ++++++++++++++++++++++++++++
mm/hugetlb.c | 41 +++++++++++++++++++++++++++++------------
2 files changed, 57 insertions(+), 12 deletions(-)

Index: linux-2.6-lttng/mm/hugetlb.c
===================================================================
--- linux-2.6-lttng.orig/mm/hugetlb.c 2008-07-10 00:23:34.000000000 -0400
+++ linux-2.6-lttng/mm/hugetlb.c 2008-07-11 10:23:48.000000000 -0400
@@ -14,6 +14,7 @@
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
+#include "hugetlb-trace.h"

#include <asm/page.h>
#include <asm/pgtable.h>
@@ -123,6 +124,7 @@ static struct page *dequeue_huge_page_vm
static void update_and_free_page(struct page *page)
{
int i;
+ trace_hugetlb_page_release(page);
nr_huge_pages--;
nr_huge_pages_node[page_to_nid(page)]--;
for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
@@ -141,6 +143,7 @@ static void free_huge_page(struct page *
int nid = page_to_nid(page);
struct address_space *mapping;

+ trace_hugetlb_page_free(page);
mapping = (struct address_space *) page_private(page);
set_page_private(page, 0);
BUG_ON(page_count(page));
@@ -205,7 +208,8 @@ static struct page *alloc_fresh_huge_pag
if (page) {
if (arch_prepare_hugepage(page)) {
__free_pages(page, HUGETLB_PAGE_ORDER);
- return NULL;
+ page = NULL;
+ goto end;
}
set_compound_page_dtor(page, free_huge_page);
spin_lock(&hugetlb_lock);
@@ -214,7 +218,8 @@ static struct page *alloc_fresh_huge_pag
spin_unlock(&hugetlb_lock);
put_page(page); /* free it into the hugepage allocator */
}
-
+end:
+ trace_hugetlb_page_grab(page);
return page;
}

@@ -288,7 +293,8 @@ static struct page *alloc_buddy_huge_pag
spin_lock(&hugetlb_lock);
if (surplus_huge_pages >= nr_overcommit_huge_pages) {
spin_unlock(&hugetlb_lock);
- return NULL;
+ page = NULL;
+ goto end;
} else {
nr_huge_pages++;
surplus_huge_pages++;
@@ -321,7 +327,8 @@ static struct page *alloc_buddy_huge_pag
__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
}
spin_unlock(&hugetlb_lock);
-
+end:
+ trace_hugetlb_buddy_pgalloc(page);
return page;
}

@@ -510,6 +517,7 @@ static struct page *alloc_huge_page(stru
set_page_refcounted(page);
set_page_private(page, (unsigned long) mapping);
}
+ trace_hugetlb_page_alloc(page);
return page;
}

@@ -1292,27 +1300,36 @@ out:

int hugetlb_reserve_pages(struct inode *inode, long from, long to)
{
- long ret, chg;
+ int ret;
+ long chg;

chg = region_chg(&inode->i_mapping->private_list, from, to);
- if (chg < 0)
- return chg;
+ if (chg < 0) {
+ ret = chg;
+ goto end;
+ }

- if (hugetlb_get_quota(inode->i_mapping, chg))
- return -ENOSPC;
+ if (hugetlb_get_quota(inode->i_mapping, chg)) {
+ ret = -ENOSPC;
+ goto end;
+ }
ret = hugetlb_acct_memory(chg);
if (ret < 0) {
hugetlb_put_quota(inode->i_mapping, chg);
- return ret;
+ goto end;
}
region_add(&inode->i_mapping->private_list, from, to);
- return 0;
+end:
+ trace_hugetlb_pages_reserve(inode, from, to, ret);
+ return ret;
}

void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
{
- long chg = region_truncate(&inode->i_mapping->private_list, offset);
+ long chg;

+ trace_hugetlb_pages_unreserve(inode, offset, freed);
+ chg = region_truncate(&inode->i_mapping->private_list, offset);
spin_lock(&inode->i_lock);
inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
spin_unlock(&inode->i_lock);
Index: linux-2.6-lttng/mm/hugetlb-trace.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-lttng/mm/hugetlb-trace.h 2008-07-11 10:24:34.000000000 -0400
@@ -0,0 +1,28 @@
+#ifndef _HUGETLB_TRACE_H
+#define _HUGETLB_TRACE_H
+
+#include <linux/tracepoint.h>
+
+DEFINE_TRACE(hugetlb_page_release,
+ TPPROTO(struct page *page),
+ TPARGS(page));
+DEFINE_TRACE(hugetlb_page_grab,
+ TPPROTO(struct page *page),
+ TPARGS(page));
+DEFINE_TRACE(hugetlb_buddy_pgalloc,
+ TPPROTO(struct page *page),
+ TPARGS(page));
+DEFINE_TRACE(hugetlb_page_alloc,
+ TPPROTO(struct page *page),
+ TPARGS(page));
+DEFINE_TRACE(hugetlb_page_free,
+ TPPROTO(struct page *page),
+ TPARGS(page));
+DEFINE_TRACE(hugetlb_pages_reserve,
+ TPPROTO(struct inode *inode, long from, long to, int ret),
+ TPARGS(inode, from, to, ret));
+DEFINE_TRACE(hugetlb_pages_unreserve,
+ TPPROTO(struct inode *inode, long offset, long freed),
+ TPARGS(inode, offset, freed));
+
+#endif
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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